credit collar 和 debit collar的区分

问题如下：

Lin Feng, 55, an executive at newly public NovaGene, built up over $100 million in company shares through various means. Half are restricted, and peer pressure limits his annual sales to $1 million. He aims to retire in five years and liquidate.

Seeking advice from Chen Hao, Feng wants to monetize and diversify without direct share sales. His cost basis is under $10 million. NovaGene shares, though newly traded, are liquid yet highly volatile, with exchange-traded and OTC derivatives as options.

For any financial move, Feng has key goals: locking in substantial gains, dodging heavy taxes, achieving wider diversification, and preventing big pre-liquidation cash outflows.

After considering a short sale and protective put, Hao devises a two-part plan. One, borrow against some shares to invest diversely. Two, use a zero-cost collar on the whole position. When Feng examines the collar terms, he wonders how to lift the upside potential without upping the downside risk.

To increase the upside potential without raising the downside risk, when dealing with the collar position, Feng should consider:

选项：

A.Narrowing the collar width B.Using a credit collar C.Adjusting the cost basis of the shares

解释：

In a credit collar, Feng can receive a net premium upfront. By structuring it properly, he can increase the potential upside of his position while maintaining the same level of downside protection. Narrowing the collar width reduces both upside and downside potential. Adjusting the cost basis of the shares is not directly related to altering the risk - reward profile of the collar.